94230 - ASTROPHYSICAL FLUID DYNAMICS

Conoscenze e abilità da conseguire

The aim of the course is to provide the student with the main theoretical tools to study the dynamics of fluids in astrophysical systems such as stars, accretion discs, galaxies and clusters of galaxies. At the end of the course the student will be familiar with the analytic modelling of hydrodynamic-equilibrium configurations of fluids in gravitational potentials, of gas flows and of hydrodynamic instabilities. In addition the student will have some knowledge of the role of magnetic fields in the dynamics of astrophysical fluids.

Contenuti

- Fundamentals of astrophysical fluid dynamics: mass, momentum and energy conservation, equation of state, gravity, cooling, heating,
thermal conduction, viscosity and turbulence .

- Equilibrium of astrophysical fluids: self-gravity and external
gravitational potentials, hydrostatic equilibrium (isothermal,
adiabatic and polytropic distributions), virial temperature, isothermal self-gravitating plane layer, self-gravitating isothermal gas sphere, rotating equilibrium (barotropic and baroclinic distributions), thin and thick discs.

- Hydrodynamic stability and instability: Eulerian and Lagrangian
perturbations, linear and non-linear perturbations, sound waves,
gravitational (Jeans) instability, convective (Schwarzschild)
instability, rotation (Rayleigh) instability, Solberg-Hoiland
criterion, thermal instability, Toomre instability.

- Gas flows in galaxies: steady inflows and outflows, shocks, gas
accretion onto black holes (Bondi accretion, Eddington limit).

- Astrophysical magnetohydrodynamics (MHD): MHD equations,
equilibrium of magnetised gas, Ferraro's law of isorotation, magnetosonic and Alfvén waves, magnetorotational instability.

Testi/Bibliografia

- M. J. Thompson "An introduction to astrophysical fluid dynamics", 2006, Imperial College Press

- J. Pringle and A. King "Astrophysical flows", 2014, Cambridge University Press

- C. Clarke and B. Carswell "Principles of Astrophysical Fluid Dynamics", 2014, Cambridge University Press

- A. Cimatti, F. Fraternali and C. Nipoti, "Introduction to Galaxy Formation and Evolution. From Primordial Gas to Present-Day Galaxies", 2019, Cambridge University Press

- F. Shu "The physics of astrophysics", 1992, University Science Books

- Binney, J., and Tremaine, S. 2008. Galactic Dynamics: Second Edition. Princeton University Press.

- Landau, L. D., and Lifshitz, E. M. 1959. Fluid mechanics

Specific sections of textbooks and articles will be suggested during the lectures. Lecture notes will be made available to the students.

Metodi didattici

Lectures

Modalità di verifica e valutazione dell'apprendimento

The assessment method will be based on an oral exam, lasting about 30-40 minutes,  in which the
student will be asked questions about three different
topics among those presented during the lectures. The oral exam
is aimed at verifying the knowledge of the theory of fluid dynamics phenomena and the understanding of the main astrophysical applications. The ability of using proper scientific language and of organising the material taking into account the available time (about 10 minutes per question) are also considered in the evaluation. If the exam is sufficient, the final mark ranges between 18/30 (barely sufficient knowledge, with modest ability of using proper scientific language and time) to 30/30 cum laude (excellent knowledge with great ability of using proper scientific language and time). The exam grade cannot be rejected more than twice.

Students with learning disabilities or temporary or permanent disabilities: please contact the relevant University office promptly (https://site.unibo.it/studenti-con-disabilita-e-dsa/it). The office will advise students of possible adjustments, that will be submitted to the professor for approval 15 days in advance. He/she will evaluate their suitability also in relation to the academic objectives of the course.

Strumenti a supporto della didattica

Blackboard and projector. Teaching material on the Virtuale online platform.

Orario di ricevimento

Consulta il sito web di Carlo Nipoti